Identification and determination the amount of phytosterols in distributed yogurts in Tehran by gas chromatography method

Phytosterols are among the most important plant sterol compounds. This study was conducted to identify and determine the amount of phytosterols in distributed yogurts in Tehran by gas chromatography method without derivatization. A total of 60 yogurt samples, including 20 pasteurized high-fat yogurt samples, 20 pasteurized cream yogurt samples, and 20 traditional high-fat yogurt samples, were collected randomly from dairy product supply centers in Tehran from January to March 2022. Then, the amount of cholesterol and four phytosterol compounds including brassicasterol, campesterol, stigmasterol, and beta-sitosterol in yogurt samples were determined using gas chromatography assay without derivatization. The results showed that the total sterols in high-fat, creamy, and traditional yogurt samples were 504.08±55.79, 816.21±51.87, and 332.8±41.22  mg/100mL, respectively. The highest and lowest percentage of cholesterol belongs to cream (%54.75±065) and traditional yogurt (%46.57±0.65), respectively(p<0.05). Also, the highest percentage of phytosterol belongs to traditional yogurt(%54.75±065) and there was a significant difference with other yogurts(p<0.05). The results also showed that the total phytosterols were more than the permissible limit of the national standard (3%) in all samples. According to the results, phytosterols are used in various yogurts distributed in Tehran, which is against the national standard of Iran. Therefore, periodic and regular evaluation of phytosterols in distributed yogurts should be done throughout the year by regulatory bodies and prevent the violation of consumers' rights.